The Principal easily gets Idiot of The Year Award. (spoilers)
She sees a dilapidated house, enters even though there's a abnormal odor emanating from the house, sees a locked door she decides to open, and notices blood on the walls as she's going up the stairs. She sees no reason to call authorities after all that? But that's okay. Her stupidity only cost her her life.
Honorable mention to Dan the cop. He knows people are getting eaten, hears "noises" coming from the shed, and decides to go on in alone anyway. Also pays the price for stupidity.
It was a pretty decent movie, tho. They did make a effort to flesh out the characters, but at the expense of horror element. Once again, a white woman saves the day.